The present invention relates to a SCARA robot.
More particularly, it relates to a SCARA robot which has robot body parts including a robot console, a first robot arm articulated on the robot console and swivelable about a first swivel axis, and a second robot arm articulated on the first robot arm and with a second swivel axis that is substantially parallel to the first swivel axis and also provided with at least one work unit. The robot further has at least one first swivel motor for swiveling an arm unit of the first and second robot arms relative to the robot console, at least one second swivel motor for swiveling the second robot arm relative to the first robot arm, and at least one working motor for actuating the work unit. The motors are controllable by a power electronics which includes electrical circuits with convertor circuits for current supply of the motors as well as with at least one control circuit for operation of the convertor circuits and thereby for controlling the motors. At least one circuit including the convertor circuit and the control circuit is arranged in at least one of the robot arms on a wall portion of a housing of the robot arm associated with the circuit.
Such a robot which is however not of a SCARA type, is disclosed for example in the European patent document EP 1 170 097 B1. Such robots are used for example on assembly lines for performance of mounting works.
A SCARA robot in which however circuits are not arranged on robot arm is disclosed in U.S. Pat. No. 5,000,653 A.
For these robots, as for manufacturing and mounting devices in general, there is a requirement to provide a maximum possible efficiency with a maximum possible compactness. This is true not only for the mechanical part of the robot, or in other words for the structural design of the robot body parts, but also for the electronics required for the operation of the robot. For reducing the required space it was proposed in the European patent document 1 170 097 B1 to arrange the drive electronics in the robot arms, and in particular with the consideration of a possible low thermal influence of the drive electronics on the robot structure, in order not to affect the movement accuracy.
It should be finally mentioned in connection with the distributed drives of a total system, the European patent document EP 1 043 643 A2 which discloses a cable system for cable connection of a cell, wherein the cell has a central module as well as drives. The central module of the disclosed cell is connectable with the electrical power network through power current conductors and can obtain informations from priority units and transfer the informations to them. The drives include electric motors and associated convertors, wherein the convertors and the electric motors each form a structural assembly. Between the drives and the central module, a star connection structure is provided, or in other words each drive is joined through its own conductor for connection with the central module. Drive current and drive informations are transmitted through this connecting conductor.
A work unit of a SCARA robot formed as a robot spindle is disclosed in the Japanese patent document JP 620 490 70. The robot spindle is both turnable around its longitudinal axis and also independently from a rotation, around the longitudinal axis is displaceable in direction of its longitudinal axis.
The hinge joints of the robot body parts with one another can be realized in a known manner with a so-called “harmonic drive” transmission, as disclosed in the German patent document DE 35 22 336. These transmissions are characterized with a high transmission ratio and clearance-free nature.